<!doctype html>
<html>
<head>
<style type="text/css">
#one {
  position:absolute;
  left:0px; top:0px;
  width:400px; height:400px;
  border:2px solid blue;
  background-color: rgb(160,160,160);
  opacity:0.8;
  z-index:1;
}
#two {
  position:absolute;
  top:100px; left:100px;
  width:200px; height:200px;
  z-index:0;
  background-color: rgb(255,0,0);
}
</style>
</head>
<body>
<div id="two"></div>
<div id="one"></div>
</body>
</html>

